In Indonesia haemorrhagic septicaemia (HS) is regarded as the most important infectious disease of cattle and buffalo. Animals in Indonesia play an important integrated role in rural communities providing fertiliser, fuel, milk and meat. They are also a source of draught power; financial security; and in, some cases, export revenue. The loss of, or reduced productivity by, even a single animal with HS can therefore have severe economic consequences for villages and individual farmers.

HS is caused by infection with Pasteurella multocida and usually occurs when the animals are under stress, such as when they are being used as draught power during the wet season. The disease has been reported from most provinces in Indonesia but diagnosis is usually based on field reports and may not be accurate.

Confirmatory laboratory diagnosis is hampered by a lack of reliable bacterial transport systems for specimens and lack of readily available HS-typing systems. In Australia, although various forms of pasteurellosis are significant diseases in pigs and poultry, little is currently known about the prevalence of Pasteurella infections in cattle.

Measures used for control and eradication of HS include antibiotic therapy as well as the widespread use of vaccines. The disease is thought to spread by exposure to asymptomatic carrier animals, which may be cattle, buffalo or other species such as pigs, sheep, and goats. The effect of vaccination on carrier animals is unknown and the success of vaccination programs is monitored by field evaluation of clinical cases and using the passive mouse protection assay. This assay is notoriously cumbersome to use, however, and the reliability of the results is uncertain.

To provide a better understanding of these issues this project will focus on the epidemiology of pasteurellosis in ruminants; the detection of Pasteurella infection; and the characterisation of Pasteurella isolates.

The project will be undertaken by the Victorian Institute of Animal Science and the Regional Veterinary Laboratory Benalla, Victoria, Australia in collaboration with the Research Institute for Veterinary Science, Bogor, and the Disease Investigation Centre, Denpasar, Indonesia.

Epidemiologists in Indonesia will conduct both a retrospective and a prospective study of the incidence of HS. Historical data will be examined for all provinces and the research team will review vaccination and management strategies used and compare them to practices in other countries.

Fresh outbreaks of HS in cattle, buffalo and pigs will be investigated for the eastern provinces of Bali and Nusa Tenggara Barat (NTB) and the disease confirmed by bacterial culture and ELISA techniques (see below). A comprehensive database will be set up.

In a sero-epidemiological study researchers will use ELISA techniques to determine the prevalence and significance of P. multocida and P. haemolytica infections in Australia and Indonesia. Up to 30 000 serum samples (including abattoir samples) will be collected under various disease control programs from dairy cattle, open range and feedlot-reared beef cattle.

Previous ACIAR projects 8382 and 8907 have included the development of ELISA systems for the detection of Pasteurella antibodies at RVL and the differentiation between HS-causing and non-HS-causing strains. The sensitivity of these assays will be further improved for the testing and detection of antigen from tissue samples and tonsillar swabs.

Scientists will investigate all aspects of the bacterial detection process including: collection of samples; transport of swabs and other specimens; and bacterial isolation, culture and identification. An alternative diagnostic method will be developed using genomic DNA and cDNA libraries generated from HS-causing and non-HS-causing strains of P. multocida.

The characterisation of Pasteurella isolates to provide information on strain variation will be undertaken using DNA analysis techniques. Researchers will also use monoclonal antibody studies to assist in an understanding of the antigens responsible for the ELISA tests and traditional serotyping assays.

It is also proposed that RVL, Benalla will provide an Australia-wide P. multocida serotyping service. As part of the research the validity of the mouse virulence assay will be assessed with various strains of P. multocida and different inbred strains of mice.

The improved diagnostic techniques and epidemiological information obtained in this study and will be utilised to provide significant benefits for farmers in Indonesia and other developing countries were the disease occurs. Indonesia will also benefit from the technology transfer from Australia.
In Australia information from this study will provide a better understanding of the disease potential in cattle as well as ensuring that the necessary techniques are available for diagnosis and typing of infections.